Jet propelled personal water craft (PWC) have become increasingly popular during recent years. They are shallow draft boats and jet skis which are propelled by impulses of high velocity water jets. The water jets are discharged through nozzles, mounted at the rear of boats. They are steered by rotating the nozzles about vertical axes with linkages or cables. The rotations of the nozzles change the directions of the water jets causing the boats to change their courses. They are generally operated within the confines of small inland lakes.
The high speeds and maneuverability of PWC are the reasons for their popularity with water sportsmen. During 1997, approximately 200,000 PWC were sold in the U.S.A. The sales constituted more than one-third of new recreational boat sales. About 1 million are in current use and their numbers are growing. 
Injuries and casualties are major problems with PWC. The National Transportation Safety Board is concerned about the safety of PWC and is searching for solutions. A major cause of the safety problems is that steering is lost when an engine fails. The loss of steering plus a lack of braking is particularly serious because of the high speeds and the manner in which PWC are operated within the confines of the small lakes. The loss of steering and lack of braking can result in a grounding of a PWC or a collision with a swimmer or other water craft.